The present invention relates to a novel type of heat exchanger incorporating plates; it also relates to the plates for making such an exchanger.
Heat exchangers developed up to the present time may be classified in two major categories, namely tubular exchangers and plate exchangers.
Plate exchangers are generally constituted by stacking a determined number of ribbed plates, of the same type, which are clamped between two bottom elements by means of tie-rods. The plates possess in their angles openings which define in the stack inlet and outlet passages for the two fluids. Alternation of the fluids in the successive spaces between the plates is obtained thanks to seals of appropriate shape.
Such exchangers present very good thermal performances for small dimensions.
However, due to the presence of seals, they cannot be used when it is desired to work at high temperature and high pressure.
French Pat. No. 1 125 663 and British Pat. No. 838 466 also propose heat exchangers incorporating independent fluid circuits constituted by juxtaposed plates disposed inside an enclosure defining independent chambers for each of the fluids, so as to form superposed channels which open out alternately in the lateral fluid circulation chambers, these channels extending over the whole width of the unit.
Numerous problems are posed in such an embodiment, namely that of the connection of the different plates to one another to form the superposed channels and that of the connection with the uprights or the like to which are fixed the lateral walls intented to form, in cooperation with said uprights and connected edges of the plates, the fluid circulation chambers. Among the solutions to this problem, mention may be made of the type of exchanger marketed for a very long time by Applicants and which is constituted by parallelepipedic blocks of graphite in which are pierced two series of channels forming circuits which are totally independent for the two fluids. These blocks present the advantage of being able to be mass-produced and of being interchangeable. Furthermore, as they are in the form of modules, they may be combined as a function of the particular applications for which the exchanger must be made. However, this type of modular exchanger presents the drawback of being made of graphite, of having a low mechanical strength and a resistance to temperature limited to 220.degree. C.